CVE-2021-43784

An integer overflow vulnerability was found in runC. This issue occurs due to an incorrect netlink encoder handling the possibility of an integer overflow in the 16-bit length field for the byte array attribute type. This flaw allows an attacker who can include a large enough malicious byte array attribute to bypass the namespace restrictions of the container by simply adding their netlink payload, which disables all namespaces.

Before runC 1.0.3, the only user-controlled byte array (used to exploit this vulnerability) was the namespace paths attributes, located in runC's config.json. Having raw access to that setting would allow the attacker to disable namespace protections entirely. This issue means that in practice, it was fairly difficult to specify an arbitrary-length netlink message with most container runtimes, resulting in the impact of this vulnerability being Low.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.